A comparison of immuncapture agglutination and ELISA methods in serological diagnosis of brucellosis

Different serological tests are used in serologic diagnosis of brucellosis. The most widely used of these are Standard Tube Agglutination and Coombs anti-brucella tests. Whereas ELISA Ig M and Ig G tests have been in use for a long time, immuncapture agglutination test has been recently introduced and used in serological diagnosis. The aim of this study was to compare diagnostic values of ELISA Ig M and Ig G and immuncapture agglutination tests with Coombs anti-brucella test.

Sera from 200 patients with presumptive diagnosis of brucellosis were included into the study. Coombs anti-brucella test, ELISA Ig M and Ig G tests and Immuncapture test were investigated in these sera. Then, sensitivity, specificity, negative predictive and positive predictive values were calculated.

Sensitivity, specificity, negative predictive and positive predictive values were found to be 90.6%, 76.3%, 94.2%, and 65.9% respectively for the Immuncapture test, whereas they were found to be 73.7%, 58.9%, 84.2%, and 42.8% for Ig G and 72.2%, 67.8%, 85.2%, and 48.7% for Ig M. The Immuncapture test was found to be compatible with ELISA Ig M and Ig G tests but it was statistically incompatible with Coombs anti-brucella test.

Immuncapture agglutination test yields similar results to those of Coombs anti-brucella test. This test is a useful test by virtue of the fact that it determines blocking antibodies in the diagnosis and follow-up of brucellosis.